Cooling arrangement for aircraft engines



1. STARKE COOLING ARRANGEMENT FOR AIRCRAFT ENGINES Filed Nov. 5, 1938 2 Sheets-Sheet 1 ,lnverzi'or fnyaberf S-far/re 4 Feb. 10, 1942. I. STARKE 2,272,526

COOLING ARRANGEMENT FOR AIRCRAFT ENGINES Filed Nov. 5, 1938 2 Sheets-Sheet 2 Jnvantor Inyoberf dfar/re Patented Feb. 10, 1942 ENGINES Ingobert Starke, Munich, Germany, assignor to the firm Bayerische Motoren Werke Aktiengesellschaft, Munich, Germany Application-November 5, 1938, Serial No. 238,952 In Germany November 3, 1937 9 Claims. (01. 244-57) This invention relates to a device for cooling air-cooled internal combustion engines arranged in nacelles or the like, and'particularly to those operating a pusher propeller.

According to the present invention air-cooled internal combustion engines mounted in closed nacelles or the like, particularly those operating a pusher propeller, are efiiciently cooled down. The basic idea and object of the invention is characterised in that the cooling air is deflected by suitable guiding means before it is supplied to the engine in the direction of flight, and then deflected again and conducted away in an opposite direction.

In this manner the cooling air is supplied to the engine in a direction from the propeller end to the anti-propeller end in the case of engines mounted oppositely to the direction of flight. From that will result the advantage that the cooling means of an engine with the cylinders arranged in rows, means which provide the said direction of the cooling air flow, will have full cooling effect.

Another object of this invention is to provide an improved arrangement for guiding cooling air to and heated air from an aeroplane engine, wherein the air guiding means and the engine are mounted wholly within the wingsand fuselage, while, at the same time, a. favorable aerodynamic shape of fuselage is maintained.

A further object of this-invention is to provide an improved arrangement for guiding cooling air to and heated air from pusher aeroplane engines housed in prop-supported nacelles.

A still further object of the invention lies in positioning the exit opening from aeroplane engines cooled by air under pressure 'in such a manner that the discharge of compressed air aids in increasing the effective lift of the aeroplane.

An additional object of the invention is to provide an improved arrangement for guiding cooling air to and heated air from aeroplane engines, wherein the aeroplane is driven by tractor and pusher engines housed in a common car or nacelle.

A more specific object in connection with the duits so that the discharge-of heated air from the tractor engine "15 not intermingled with the,

entrance of the cooling air for the pusher engine.

A general object of the entire subject matter of the present invention is to provide an aerodynamically sound, heat-conductively correct arair from an aeroplane engine in such a manner that the discharge of heated air cannot intermingle with the fresh entering cooling air.

Other objects will become apparent from the following description taken in connection with the attached drawings showing several illustrative embodiments of the invention, and wherein:

Fig. 1 is a top plan view, partially in cross-section, of an aeroplane having a pusher,engine mounted within the wing or fuselage, and embodying a preferred cooling arrangement accord.

ing to the present invention;

Fig. 2 is a side view, partially in cross-section, of a pusher engine mounted in a car or nacelle upon a prop, and illustrating a modified form of the cooling air arrangement according to the present invention;

.Fig. 3 is a side view, partially in cross-section, similar to Fig. 2 but illustrating a still further modified arrangement;

Fig. 4 is a side view, partially in cross-section,

illustrating the application of the principles of the present invention to an' aeroplane having tractor and pusher engine mounted in a single car or nacelle and supported by a prop; and

Fig. 5 is a transverse cross-sectional view through a car, or nacelle containing both tractor and pusher engines, illustrating an arrangement for the entry of cooling air and discharge of heated air from such engines, according to the present invention.

In Fig. 1 the fuselage I of the aircraft is giventhe form similar to a nacelle or car, and fitted with an air-cooled engine 2 driving the pusher propeller 3. The inlet apertures l and 5 for the cooling air are arranged in the forward portion of the wing of the aircraft.

The cooling air is deflected with the help of the guiding channels 6 and 1 arranged inside the wings and conducted to the engine 2 in the direction of flight. The air warmed up in passing over the engine 2 is again carried away through the channels 8 and 9 to the discharging apertures in the rearwardly facing trailing edge of the wing.

The advantage of this arrangement consists in the fact that the engine and the guiding means for the cooling air are wholly housed in the wing and in the fuselage, and thereby the most-favorable aerodynamic shape of the fuselage is obtained. At the same time thereis no opportunity for the discharge heated air to commingle with the entering fresh air.

from the engine 2 housed in a nacelle or car it) rangement for guiding 'cooling air to and heated connected to the aircraft by means of a' prop l0.

The cooling air is taken in through air hoods l2, then conducted to the engine 2 in the direction of flight and carried away 'at the rear l3 of the car prop Ill.

This arrangement has the advantage that the engine and the cooling conduits are arranged closely together and that a plurality of similar power cars can then be readily positioned on the aircraft. At the same time it will be noted that again in this construction there is no opportunity for the heated discharged air to commingle with the fresh entering air.

Fig. 3 shows a nacelle or car H which is likewise equipped with an engine 2 driving a pusher propeller 3. To further the cooling air circulation the engine is fitted with a ventilator M which sucks in the cooling air, for example through the air hood I2, forcing it in the direction of flight to pass over the engine 2, then carrying it through a separate channel l5 to the outlet I6 in the wing I! where it is discharged, thus causing an increased lifting effect. In this case the outlet aperture I6 is in the top side of wing where the depression is increased owing to the absence of eddies otherwise occurring.

Fig. 4 shows a power car, l8 equipped with two air-cooled radial engines 2 and I9, one 2 of which is driving a pusher propeller, whilst the other I9 drives a tractor propeller 20. The power car I8 is connected to the aircraft by means of the prop 2|- The cooling air taken in through the air hoods I2 is conducted in the direction of flight to the rear engine 2 driving the pusher propeller 3, and is again carried away at the rear 22 of the car prop 2|. The said discharging aperture for the cooling air is fitted with adjustable flaps 23. The cooling air is supplied through the engine cowling to the radial engine l9 arranged in front of the power car and driving the tractor propeller 20 in the usual manner, and again conducted away through an adjustable slot 25 arranged in the frontal edge of the car prop.

Through the medium of the adjustable slots and controllable flaps, the sectional area of the discharging apertures and the difference between inlet pressure and discharging pressure may be varied. When flowing fast the regulating devices will be in a nearly closed condition, which results in a strongly reduced air resistance,though affording sufficient passage of the cooling air. When flying slowly and when taking off, or if the temperature of the surrounding air is high, the said regulating devices may be opened widely to increase the quantity of air flowing through them.

Fig. 5 shows a cross sectional view of a power car similar to that in Figure 4, with the excep tion that in this case the cooling air of the front engine is carried away through adjustable discharging apertures in the power car itself. The discharging apertures for the cooling air for the front engine driving the tractor propeller are arranged in every part of the car circumference not used for the cooling air, inlet apertures for the rear engine driving the pusher propeller. In this view the annular inlet aperture for the cooling air is shown at 26, the apertures arranged in a part of the car surface for discharging the cooling air having passed over the front engine are numbered 21, whilst 28 are the inlet apertures and 29 the outlet apertures for the rear engine. As is true in the other forms of construction proposed, the cooling air entrances and heated air exits are so arranged that there is no chance of intermingling of the heated discharged air with the entering cooling air.

While I have herein shown and described only certain embodiments of certain features of my present invention, it is to be understood that they are to be regarded merely as illustrative, and that I do not intend to limit myself thereto except as may be required by the claims which follow.

The invention claimed is:

1. In an aircraft, a nacelle, an engine for said aircraft mounted in said nacelle, a pusher propeller driven by said engine, and means for cooling said engine including at least one air-guiding entrance canal open forwardly of said propeller in the direction of flight of said aircraft to freely receive the oncoming air and reversely curving the same to direct the air over said engine in' the direction of flight of said aircraft, and means including at least one exit canal receiving the said air from the front of the engine and reversely the same to guide and disporting wing having an opening in its leading edge for the receiving end of said entrance canal. 3. In an aeroplane having a flight-supporting wing, an engine for said aeroplane, a pusher prohaving an opening in its top surface, a nacelle, an

peller driven by said engine, and means for cooling said engine including an air-guiding entrance canal open at one end in the leading edge of said wing and reversely curving the air to discharge the same over said engine in the direction of flight of said aeroplane, and means including an exit canal guiding the heated air from the front of the engine and reversely curving said air to discharge the same, said exit canal having its discharging mouth in the trailing edge of said wing.

4. The combination according to claim 1, in which said aircraft is provided with a flight-supporting wing having an opening in its upper surface for the discharge of said exit canal.

5. In an aeroplane, a flight-supporting wing, a nacelle, an engine mounted in said nacelle, a pusher propeller driven by said engine, a prop for mounting said rr'acelle above said wing, and means for cooling said. engine, including at least one air-guiding entrance canal on said nacelle, open in the direction of flight of said aeroplane to receive the oncoming air, and'ieversely curving the same to direct the air over the said engine inthe direction of flight of said aeroplane, and means including at least one exit canal receiving the heated air from the front of the engine and reversely curving the same to guide and discharge said air through said prop toward the rear of said aeroplane.

6. In an aeroplane, a flight-supporting wing engine mounted in said nacelle, a pusher propeller driven by said engine, a prop for mounting said nacelle above said wing, and means for cooling said engine including at least one air-guiding entrance canal on said nacelle, open in the direction of flight of said aeroplane to receive the oncoming air, and reversely curving the same to direct the air over said engine in the direction of flight of said aeroplane, means including an exit canal for receving the heated air from'the front of the engine and reversely curving the same to guide and discharge said air real-wardly and upwardly through the opening in said wing, and means for positively drawing the air through said entrance canal, forcing it over said engine and discharging it through said wing opening.

7. In an aeroplane, a flight-supporting wing, a nacelle, a pair of engines mounted in said nacelle, tractor and pusher propellers respectively driven by said engines, a prop for mounting ,said nacelle above said wing, an inlet for guiding air to said traction engine, a discharge canal having an opening about a portion of the'circumference of said nacelle for discharging the heated tractor engine air, means including an entrance canal open in the direction of flight of said aeroplane for reversely curving entering cooling air to direct the same over said pusher engine in the direction of flight of said aeroplane, and an exit canal receiving the heated air from the front of said pusher engine and reversely curving the same to guide and discharge said air rearwardly, said entrance extending about the circumference of the nacelle except in that portion thereof overlapping the longitudinal projection of the discharge canal from the tractor engine.

8. In an aircraft, a nacelle, an engine for said aircraft mounted in said nacelle, a pusher propeller driven bysaid engine, and means for cooling said engine including two air-guiding entrance canals dividedfrom one another and open in the direction of flight of said aircraft to freely receive the oncoming air and reversely curving to direct the air over said engine in the direction of flight of said aircraft, and means including two exit canals receiving the said air from the front 01 v the engine, divided from one another and reversely curving the'same to guide and discharge said air toward the rear of said aircraft, the discharging end of said exit canals opening substantially rearwardly of said engine and rearwardly of the opening to said entrance canals. 9. In an aeroplane having a flight-supporting wing, an engine forsaid aeroplane, a pusher propeller driven by said engine, and means for cooling said engine including two air-guiding entrance canals open at one end in the leading edge of said wing, divided from one another and reversely curving entering cooling air to discharge the same over said engine in the direction 0! flight of said aeroplane, and means including two exit canals for guiding the air from the front of the engine and reversely curving the same to guide and discharge said air toward the rear of said aeroplane, said exit canals being divided from one another and having their discharging mouths in the trailing edge of said wing.

INGOBERT STARKE. 

